1. Field of the Invention
The present invention relates generally to cytokines. More specifically, the present invention relates to a novel cytokine with broad anti-neoplastic activity.
2. Description of the Related Art
Cell growth appears to be regulated by a balance between growth stimulatory and growth inhibitory molecules. An imbalance in these growth regulatory cytokines has been proposed as one of the mechanisms of tumor growth.
Several cytokines which stimulate the growth of tumor and normal cells have been described. These include, e.g., epidermal growth factor (EGF), fibroblast growth factor (FGF), platelet derived growth factor (PDGF), insulin-like growth factors (IGF), interleukins (IL), colony stimulating factors (CSF) and transforming growth factors (TGF-.alpha. and TGF-.beta.).
In contrast, other cytokines selectively inhibit the growth of certain tumor cells. These include, e.g., interferons (IFN), lymphotoxin (LT), tumor necrosis factor (TNF), oncostatin M, amphiregulin, interleukin-1 (IL-1), interleukin-6 (IL-6) and TGF-.beta..
These growth stimulatory and growth inhibitory cytokines can be differentiated from each other based on their source, their specificity against tumor targets, their physio-chemical properties and their primary structure. Thus, the identification and characterization of growth regulatory cytokines is of critical importance in the understanding of cellular growth, including growth of neoplasms.